Tailstock and feed means therefor

ABSTRACT

A tailstock in which the work is firmly held in blocks which are biased together by hydraulic and/or spring means. A formula for determining whether the workpiece will be held within the blocks during friction or inertia welding. Work is fed into the rear of the tailstock from a hopper and delivery means when the pressure forcing the blocks together is temporarily relaxed.

United States Patent Calvin D. Loyd Peoria;

Ronald L. Satzler, Metamora, both of, 111. 783,043

Dec. 1 l 1968 June 15, 1971 Caterpillar Tractor Co.

Peoria, ll].

Inventors Appl. No. Filed Patented Assignee TAILSTOCK AND FEED MEANSTHEREFOR 9 Claims, 6 Drawing Figs.

US. Cl 228/2, 29/4703, 228/2, 269/234, 279/4 Int. Cl. 823k 23/00 Fieldof Search 279/4; 269/20, 25, 26, 30, 3 I 234; 228/2; 29/4703; 156/73[56] References Cited UNITED STATES PATENTS 2,480,762 8/1949 Parker279/4 X 2,850,926 9/1958 Jobe 269/234X 3,192,600 7/1965 Jones 269/234 X3,234,646 2/ 1966 Hollander et a1. 29/4703 3,235,162 2/1966 Hollander228/2 3,435,510 4/1969 Oberle et al. 29/4703 Primary Examiner-John F.Campbell Assistant ExaminerRobert J. Craig Attorney-Fryer, Tjensvold,Feix, Phillips and Lempio ABSTRACT: A tailstock in which the work isfirmly held in blocks which are biased together by hydraulic and/orspring means. A formula for determining whether the workpiece will beheld within the blocks during friction or inertia welding. Work is fedinto the rear of the tailstock from a hopper and delivery means when thepressure forcing the blocks together is temporarily relaxed.

PATENTEUJUNISIQ?! 35847.

SHEET 1 OF 4 INVENTORS CALVIN D. LOYD RONALD L. SATZLER ATTORNEYSPATENTED JUN} 5 |97| SHEET 2 OF 4 4 vmm mw 6 C INVENTORS CALVIN D. LOYDRONALD L. SATZLER ATTORNEYS PATENIEB JUN 1 5|97| 3584-??? saw a or 4INVENTORS CALVIN D. LOYD RONALD L. SATZLER BY 4 24, 7% r41,

ATTORNEYS Ill PATENTEDJUHI 5197! 3584777 sum u 0F 4 I-IIIQIZQL;

INVENTORS VIN D. LOYD ALD L. SATZLER ATTORNEYS TAILSTOCK AND FEED MEANSTHEREFOR SUMMARY OF THE INVENTION Although there are many applicationsfor automatically fed tailstocks, it is becoming increasingly importantthat such devices be provided in machines capable of performing frictionor inertia welding as described in U.S. Pat. No. 3,273,233. In order touse these machines in the most efficient manner, it is necessary thatthere be no lost time due to hand loading or chucking of the workpieces.It is also preferable that mechanisms used for automatic clamping andholding of the nonrotating weld pieces be as uncomplicated as possible.On the other hand, in view of the great forces generated and thenexhausted at the interface of the weld pieces, themachinery must produceadequate holding forces without allowing slippage of the stationary weldpiece.

It is therefore an object of this invention to provide such a tailstockwhich is relatively simple in design and economical to manufacture andmaintain.

It is also an object of this invention to provide such'a tailstock whicheliminates lost time due to hand loading and chucking of the stationaryworkpiece.

It is a further object of this invention to provide such a machine whichobviates the need for complicated loading arms and mechanisms and thecircuitry required therefor.

It is also an object of this invention to provide such a means whichutilizes the welding thrust force to increase the clamping forcesexerted on the nonrotatable weld piece in a friction or inertia weldingmachine.

It is a still further object of this invention to provide such a devicewhich produces precise centering of the nonrotatable weld piece with therotatable weld piece.

It is also an object of this invention to provide such a machine inwhich the nonrotatable weld piece is automatically loaded and the weldedproduct is automatically ejected from the tailstock.

It is also an object hereof to provide a method and formula fordetermining that the workpiece will be satisfactorily held between theblocks during friction or inertia welding.

Other objects and advantages of the present invention will becomeapparent from the following description and claims as illustrated in theaccompanying drawings which, by way of iilustration, show a preferredembodiment of the present invention and principles thereof and what isnow considered to be the best modes contemplated for applying theseprinciples. It is recognized that other embodiments of the inventionutilizing the same or equivalent principles may be used and structuralchanges may be made as desired by those skilled in the art withoutdeparting from the present invention and purview of the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a plan view of thetailstock assembly and work feed means therefor;

FIG. 2 is a sectional side view of the automatic work feeding means;

FIG. 3 is a partial front view of the workholding assembly;

FIG. 4 is a plan view of an alternate embodiment of the tailstock;

FIG. 5 is a view, similar to FIG. 3 of the alternate embodiment; and

FIG. 6 shows a side view of the alternate workholding device withemphasis placed in this figure on the hydraulic portion of the device.

Referring now to the drawings in greater detail, FIG. 1 shows atailstock assembly 10 consisting mainly of a workholding assembly 12, aback plate 14, hydraulic cylinders 16 and 18 with corresponding pistonrods 20 and 22, and an automatic loading mechanism 24. Two parallel tiebars 26 and 28 connect the tailstock assembly 10 to the headstock (notshown) of the machine.

-The parallel tie bars 26 and 28 pass through the workholding assembly12, and this assembly is connected to the tie bars by means of linearmotion ball bushings contained within a base member 30. These bushingsallow the assembly 12 to travel along the tie bars when hydraulic fluidis supplied to the cylinders 16 and 18. As will be shown, the motion ofassembly 12 along the tie bars causes the loading, positioning, andthrust required to weld the nonrotatable weld piece 32 to a rotatablepiece (not shown) in a well-known manner. With one weld piece 32 beingwelded during each cycle of operation, several other workpieces 33 aremaintained in a position behind the piece currently being welded.

The workholding assembly 12 is comprised of several members includingthe base 30, two tapered V-blocks 34 and 36, two tapered wedge blocks 38and 40, a plate 42, and two small hydraulic cylinders 44 and 46. Thebase 30 is connected to the tie bars 26 and 28 as previously mentionedand is further connected to the hydraulic piston rods 20 and 22 by meansof flanges 48 and 50.

The piston rods 52 and 54, of cylinders 44 and 46 respectively, are eachattached by a pivot joint (not shown) to base 30, while the head ends ofthe cylinders are fastened to the tapered V-blocks 34 and 36. Thetapered wedge blocks 38 and 40 are also fastened to base 30 by means ofbolts 56 and 58. Shim packages 60 and 62 positioned between the taperedwedge blocks and base 30 control the centering of the weld pieces 32between the tapered blocks 34 and 36. It is noted that the blocks 34 and36 may be of any convenient workholding shape, but have been illustratedas V-blocks for the purposes of this disclosure. The centering of aworkpiece between the blocks would normally be necessary only wheninitially setting up the machine. So as to insure accurate cooperationof the blocks, a pin is mounted within a recess in each block, therebyinsuring that the axial movements of the blocks are coordinated.

In FIG. 3, a front view of the workholding assembly 10 is shown. Thisfigure illustrates how the parallel tie bars 26 and 28 pass through thebase member 30 and how the linear motion ball bushings 72 and 74encircle the tie bars. The blocks 34 and 36, the wedge blocks 38 and 40,bolts 56 and 58, weld specimen 32, and top plate 42 and bottom plate 76are also clearly illustrated. The blocks 34 and 36 are fitted so as toslide freely between plates 42 and 76.

The tapered mating faces between the tapered blocks 34 and 36 and thewedge blocks 38 and 40 dictate that if enough force is applied to thetapered blocks to cause them to move to the left, in FIG. 1, a clampingforce will be produced on the weld piece 32. For reasons which willbecome obvious, it is desirable to have a clamping load on the weldpiece at all times. Therefore, a preloaded spring 45 is situated insideeach of the small hydraulic cylinders 44 and 46 and it exerts a pressurebetween the normally stationary pistons and the movable housing in eachcylinder. Thus, the tapered blocks have a force exerted on them at alltimes in order to hold the weld piece 32 with a clamping force.

In addition to the constant force exerted by the blocks on the weldpiece 32, a much more intense clamping force is exerted on the weldpiece by the blocks at the time of welding to the rotating weld piece.This larger clamping force is provided by the thrust force, which causesthe blocks to tighten their grip on weld piece 32 and is also providedby supplying the two small hydraulic cylinders 44 and 46 with the samehydraulic fluid pressure which is applied to the tailstock movingcylinders 16 and 18. In this way the large welding thrust force is usedto advantage to clamp and hold the nonrotating weld member during thewelding operation.

The above phenomena will occur when the tapered blocks 34 and 36 andwedge blocks 38 and 40 are suitably designed. Such a design might, forexample, be formulated by utilization of an equation such as:

' 1 W 2 (HR)? where:

9 One-halfU/z) the included angle of the wedge blocks as illustrated inFIG. I of the drawings.

1) The angle between the lines of contact between the V- blocks and theweld piece and a line perpendicular to the direction of the clampingforce as illustrated in FIG. 3 of the drawings.

[.L Coefficient of friction between the V-blocks and the wedge blocks.

a, Coefficient of friction between the V-blocks and the weld piece.

T= One-half 6) of the welding thrust force (lbs).

P The total force exerted on one wedge block by both the preload springand the small hydraulic cylinder attached to the wedge block when thecylinder is pressurized.

W= The maximum torque value produced during a weld, as

determined experimentally and measured in (lb.in.).

D= Diameter of the weld piece (inches).

Since, in most cases, the factors relating to the weld member (T, P, W,and D) are relatively fixed or not easily changeable, the factorsrelating to the wedge and V-blocks (9, 1 t, and u are normally theparameters which are changed, if necessary. In other words, for a givenset of parameters, if it is determined from the equation that the V-blocks will not hold the weld piece from slipping during the weld thrustapplication, then the parameters relating to the wedge or V-blocks, orboth, must be changed.

The most logical values to change would be the angles and/or I which areassociated with the wedge and V-blocks. The coefficient of friction canbe changed, but only within limited ranges.

If desired, the equation may be rewritten as:

(T+7))(COS 0-11,, Sin 0);; Cos (H-Sin o Th) From this equation, theangle 1 may be determined and selected and most materials can be held inthe machine simply be selecting Vblocks in accordance with the requiredangle.

There is shown in FIG. 2 a more detailed illustration of the automaticloading mechanism 24 which consists primarily ofa holder or hopper 64which holds a supply of workpieces 33, a tubular member 66, and a plate68 which is fastened to the tubular member and is situated under thehopper. The tubular member or chute 66 passes through a hole in the base30 and is attached to the base by means of a flange 70. The workpieces33, which are stacked in the hopper 64 rest on top of one another withthe very bottom piece resting on the top of plate 68. The front portionof chute 66 is a full circular tube, whereas the back portion which isfastened to the plate is a troughlike member or semicircular piece.

In operation, with the tailstock assembly in the condition shown in FIG.I, i.e., with a weld piece 32 held in the blocks 34 and 36 and severalworkpieces laying loosely behind the piece to be welded, the headstockof the welding machine which holds the rotatable weld piece is broughtto the proper speed for welding. When the headstock of the inertia orfriction welding machine has reached the proper velocity for welding,power to the motor driving the headstock is discontinued, and at thesame time, hydraulic fluid is supplied to cylinders 16 and 18 of thetailstock workholding device, causing piston rods 20 and 22 to move tothe right, thereby forcing the entire workholding assembly 12 to theright or toward the rotating weld member.

At the same time that the hydraulic fluid is communicated to cylinders16 and 18, a portion of this fluid under the same pressure is alsocommunicated to the smaller hydraulic cylinder 44 and 46 through a line78. Line 78 may be fed through any suitable means, but is shownconnected to the end of piston rod 20 which may have a hollow passagetherein so that the fluid passes through the rod and into line 78. Thus,the small hydraulic cylinders are pressurized at the same time that thelarger cylinders are pressurized. The pressure in the smaller cylindercauses the cylinder housing to move to the Sin (b;

left and since the tapered blocks are fastened to the cylinder housings,they are also forced to the left causing them to grip the weld member 32more tightly. As the weld pieces are brought together, an additionalclamping force is transmitted, due to the welding thrust, through weldpiece 32 to the blocks causing them to tend to move to the left and thusgrip even 'more tightly. These combined forces acting on weld piece 32will prevent any slippage during the welding operation. There is enoughspace between the workpieces behind weld piece 32 to allow the requiredmovement to the left of blocks 34 and 36. Without space between theworkpieces, the weld thrust force would be communicated through theworkpieces to chute 66 and prevent blocks 34 and 36 from clamping andholding weld piece 32.

When the weld has been completed, the rotating headstock has come torest and the chuck or fixture holding the rotating member loosened, thehydraulic pressure is released from the four cylinders. Since the axialwelding force and the hydraulic holding force on the weld piece have nowbeen released, the weld piece is held within the blocks only by thepressure of springs 45 within the smaller cylinders.

At this time cylinders 16 and 18 are pressurized on the opposite side ofthe piston thereof causing rods 20 and 22 to be drawn into thecylinders. This in turn draws the workholding assembly 12 to the left,or toward plate 14. As the assembly 12 moves to the left, plate 68 willmove from underneath hopper 64 and chute 66 will become positionedbeneath the hopper. As the chute moves underneath the hopper, the lastworkpiece 33 in the trough will abut the forward area of the bottomworkpiece 33 held in the hopper 64.

Referring to FIG. 2, the abutting surfaces are designated as 82 and 84respectively. Since the workpiece 33 in the hopper cannot move to theleft as the chute continues to move toward the left, a force is exertedbetween the two pieces at the abutting surfaces 82 and 84. This force istransmitted to the workpieces further on in the chute, thereby forcingthe welded piece 32 out of the blocks 34 and 36 while the next workpiece33 moves into the blocks, becoming the new weld piece 32. Properselection of springs 45 will allow the abutment force to overcome thepreloads of the springs and thereby allow the weld pieces to passbetween the blocks.

As chute 66 continues to move under the hopper, the trough will movedirectly under the bottom workpiece 33 which will drop into the chute.At this time movement of the assembly 12 stops and the hydrauliccylinders 16 and 18 are again pressurized to move the assembly 12 towardthe welding position, thereby causing plate 68 to move to the right.Surface 69 on plate 68 will abut the bottom workpiece 33 and move it tothe right out of hopper 64. The next piece above the bottom workpiece 33is prevented from moving out of hopper 64 by block 65. As the bottomworkpiece 33 moves out of hopper 64, the next piece drops down ontoplate 68. The bottom workpiece can clear block 65 only after droppinginto the v trough of chute 66.

During the automatic loading of the tailstock, another rotatable weldpiece will have been placed in the headstock of the machine and clampedready for welding. The tailstock assembly then continues to move towardsthe rotatable piece until it is in position for welding of the nextassembly, and the cycle may once again be repeated. It should berealized, that cylinders 44 and 46 could be eliminated if the taperedblocks are suitably designed, e.g., if the above equation is satisfied,but some device would still be needed for preloading the blocks for thepurpose disclosed.

A modification of the workholding device is shown in FIGS. 46. Forpurposes of illustration, the automatic loading mechanism has beenomitted in these figures for simplicity.

In FIG. 4 there is shown a tailstock of an inertia or friction weldingmachine with a workholding assembly 112 for holding a nonrotatable weldpiece during the welding process.

The assembly 112 contains two small hydraulic cylinders 144 I and 146,two tapered V-blocks 134 and 136, and two tapered wedge blocks 138 and140. Two plate assemblies 142 and 143 may be bolted to the casting andare situated above the tapered wedge blocks 138 and 140 and the taperedV-blocks 134 and 136.

It can be seen from FIG. 5 that plates 142 and 143 have been designed tofacilitate the loading and unloading of the workpieces into the blocksif it should be desired to load the blocks from above. In FIG. 4, plateassembly 142 has been partly removed to show the details of the wedgeblock 138 and the block 134.

Hydraulic cylinders 144 and 146 are fastened on one end to casting 130by assemblies 204 and 206 and on the other end to blocks 134 and 136 byassemblies 108 and 111.

The hydraulic cylinders 144 and 146 differ from cylinders 44 and 46 ofthe initial embodiment in that either side of the piston in thecylinders can be pressurized with hydraulic fluid and they contain nosprings therein,

Referring to FIG. 6 it can be seen that the system for pressurizingcylinders 144 and 146 includes a manifold 186 with a port 188 and line178 leading to a port 192 in the rod end of cylinders 144 and 146 and aport 194 and line 179 leading to ports 198 in the head end of thecylinders. Through this arrangement, the introduction of hydraulic fluidinto the cylinders through ports 198 will cause the blocks 134 and 136to move to the right and loosen the weld specimen, whereas introductionof hydraulic fluid into the cylinders through ports 192 will cause theblocks to move to the left and tighten onto the weld piece.

In order to facilitate a more rapid release of the weld piece aftercompletion of the weld, a relief 210 has been machined near the centerof each of the wedge blocks 138 and 140, and somewhat similar reliefs212 have been machined near the center of the tapered area of blocks 134and 136. When the hydraulic cylinders force the blocks to the right asshown in the drawings, in order to release the weld specimen, shoulders214 of the tapered blocks will slide into the reliefs 210 of the wedgeblocks and shoulders 216 of the wedge blocks will slip into reliefs 212of the tapered blocks. This allows the blocks to be opened a relativelylarge distance and the weld piece can easily be removed from thefixture, Thus, the distance which the blocks must travel for suchrelease is greatly reduced.

The separation of the blocks is aided through the use of coil springs220 and 222 and a guide pin 224. The springs are placed inside drilledholes of the blocks so that when the blocks are clamped onto a weldspecimen, the springs are compressed a predetermined amount. When theweld is completed and the blocks are being opened to remove thespecimen, the coil springs 220 and 222 force the blocks into the reliefsso that the blocks open quickly. If desired, the springs could bereplaced by other suitable means such as, for example, a small rollerattached to each block and allowed to roll in a specifically shapedstationary cam slot.

Pin 224 is provided to insure the blocks work together and close at thesame rate upon the weld piece. It may, therefore, be pressfltted intoone of the V-blocks and loosely fitted into the other.

Although the alternate embodiment of FIGS. 4-6 does not show theautomatic loading mechanism, it is obvious that the mechanism could beused with this tailstock assembly.

Thus has been disclosed an automatic tailstock and feeding device whichpermits a far more economical usage of a friction or inertia weldingmachine than has heretofore been available. The invention provides arelatively low cost, uncomplicated system which obviates lost time dueto hand loading and chucking. While preferred embodiments of theinvention have been described, other variations and modificationsthereof falling within the purview of the following claims will beobvious.

We claim:

I. In a tailstock assembly, a base member, a pair of wedge blockssecured to the base member, a pair of tapered blocks each having awork-gripping surface thereon slidably positioned adjacent the wedgesurface of a wedge block with said work-gripping surface facing awayfrom said wedge block, actuatin means fastened to said tapered block andsaid base where y actuation of the actuating means move the taperedblocks in a direction parallel to the axis of a workpiece due to theforce of the actuating means and also in a direction perpendicular tosuch axis due to the reactions with the wedge blocks, and meansinterconnecting said tapered blocks so as to insure that said taperedblocks move parallel to the axis of the workpiece in equal incrementswhen said actuating means is actuated.

2. The assembly of claim 1 including means biasing said tapered blocksaway from one another.

3. The assembly of claim 1 including means in said actuating meansbiasing said tapered blocks into a workpiece gripping position.

4. The assembly of claim 1 including means in said wedge blocks and saidtapered blocks allowing greater movement in said perpendicular directionthan allowed merely by the angle of taper therebetween.

5. in a tailstock assembly, a base member, a pair of wedge blockssecured to the base member, a pair of tapered blocks each having awork-gripping surface thereon slidably positioned adjacent the wedgesurface of a wedge block with said work-gripping surface facing awayfrom said wedge block, actuating means fastened to said tapered blockand said base whereby actuation of the actuating means move the taperedblocks in a direction parallel to the axis of a workpiece due to theforce of the actuating means and also in a direction perpendicular tosuch axis due to the reactions with the wedge blocks, and includingmeans for feeding workpieces to said tailstock comprising a feed membermounted on said base member in such a position as to pass a workpiecethrough said base, the distal end of said feed member having meanstherein for receiving a workpiece, and a hopper means mounted above saidreceiving means for depositing workpieces therein.

6. The assembly of claim 5 including means for moving said base memberand the structure attached thereto relative to said hopper.

7. The assembly of claim 5 including means attached to the distal end ofsaid feed member for closing said hopper when said receiving means isnot in receiving relationship relative to said hopper.

8. The assembly of claim 6 including means in said hopper causing theejection of said workpiece from said gripping surfaces when said basemember is moved toward said hopper.

9. A tailstock assembly for a friction welding machine of the kind inwhich the end surfaces of two parts to be welded are held in a rotatableheadstock and a nonrotatable tailstock and are pressed together in arotative rubbing contact under an axial load to heat the end surfaces toa weldable condition, said assembly including a base member, loadingmeans for producing an axial load on the parts to be welded by movingthe base member axially toward the headstock of the friction welder, apair of wedge blocks secured to said base, a pair of tapered blocks eachhaving a work-gripping surface thereon slidably positioned adjacent thewedge surface of a wedge block with said work-gripping surface facingaway from said wedge block, said loading means being connected to saidtapered blocks and said base whereby actuation of said loading meansmoves said tapered blocks in a direction parallel to the axis of aworkpiece due to the force of said loading means and also in a directionperpendicular to such axis due to the action from said wedge blocks toexert a gripping force on a part to be welded which is positionedbetween the gripping surfaces of the pair of tapered blocks.

1. In a tailstock assembly, a base member, a pair of wedge blockssecured to the base member, a pair of tapered blocks each having awork-gripping surface thereon slidably positioned adjacent the wedgesurface of a wedge block with said workgripping surface facing away fromsaid wedge block, actuating means fastened to said tapered block andsaid base whereby actuation of the actuating means move the taperedblocks in a direction parallel to the axis of a workpiece due to theforce of the actuating means and also in a direction perpendicular tosuch axis due to the reactions with the wedge blocks, and meansinterconnecting said tapered blocks so as to insure that said taperedblocks move parallel to the axis of the workpiece in equal incrementswhen said actuating means is actuated.
 2. The assembly of claim 1including means biasing said tapered blocks away from one another. 3.The assembly of claim 1 including means in said actuating means biasingsaid tapered blocks into a workpiece gripping position.
 4. The assemblyof claim 1 including means in said wedge blocks and said tapered blocksallowing greater movement in said perpendicular direction than allowedmerely by the angle of taper therebetween.
 5. In a tailstock assembly, abase member, a pair of wedge blocks secured to the base member, a pairof tapered blocks each having a work-gripping surface thereon slidablypositioned adjacent the wedge surface of a wedge block with saidwork-gripping surface facing away from said wedge block, actuating meansfastened to said tapered block and said base whereby actuation of theactuating means move the tapered blocks in a direction parallel to theaxis of a workpiece due to the force of the actuating means and also ina direction perpendicular to such axis due to the reactions with thewedge blocks, and including means for feeding workpieces to saidtailstock comprising a feed member mounted on said base member in such aposition as to pass a workpiece through said base, the distal end ofsaid feed member having means therein for receiving a workpiece, and ahopper means mounted above said receiving means for depositingworkpieces therein.
 6. The assembly of claim 5 including means formoving said base member and the structure attached thereto relative tosaid hopper.
 7. The assembly of claim 5 including means attached to thedistal end of said feed member for closing said hopper when saidreceiving means is not in receiving relationship relative to saidhopper.
 8. The assembly of claim 6 including means in said hoppercausing the ejection of said workpiece from said gripping surfaces whensaid base member is moved toward said hopper.
 9. A tailstock assemblyfor a friction welding machine of the kind in which the end surfaces oftwo parts to be welded are held in a rotatable headstock and anonrotatable tailstock and are pressed together in a rotative rubbingcontact under an axial load to heat the end surfaces to a weldablecondition, said assembly including a base member, loading means forproducing an axial load on the parts to be welded by moving the basemember axially toward the headstock of the friction welder, a pair ofwedge blocks secured to said base, a pair of tapered blocks each havinga work-gripping surface thereon slidably positioned adjacent the wedgesurface of a wedge block with said work-gripping surface facing awayfrom said wedge block, said loading means being connected to saidtapered blocks and said base whereby actuation of said loading meansmoves said tapered blocks in a direction parallel to the axis of aworkpiece due to the force of said loading means and also in a directionperpendicular to such axis due to the action from said wedge blocks toexert a gripping force on a part to be welded which is positionedbetween the gripping surfaces of the pair of tapered blocks.